Due to the fast melting of glaciers around the world, it is important to characterize the evolution of the meltwater circulation beneath them as it highly impacts their velocity. By using very high-resolution satellite images and field measurements, we modelized it for two Svalbard glaciers. We determined that for most of Svalbard glaciers it is crucial to include their surface morphology to obtain a reliable model, which is not currently done. Having good models is key to predicting our future.

In this paper, we present new models to depict ground ice in permafrost in Canada, incorporating knowledge from recent studies. The model outputs we present reproduce observed regional ground ice conditions and are generally comparable with previous mapping. However, our results are more detailed and more accurately reflect ground ice conditions in many regions. The new mapping is an important step toward understanding terrain response to permafrost degradation in Canada.

This paper provides a characterization of the physical and optical properties of "rotten" Arctic sea ice collected in two field seasons from off the coast of Utqiaġvik (formerly Barrow), Alaska. Rotten ice is physically and optically distinct when compared to ice from earlier in the melt season. It is marked by large connected pores, has lost most of its brine content, and scatters more light. This fragile, permeable ice type may become increasingly important in a warming Arctic.

Many glaciers in southern Alaska and the Yukon experience changes in flow speed, which occur in episodes or sporadically. These flow changes can be measured with satellites, but the resulting raw velocity products are messy. Thus in this study we developed an automatic method to produce a synthesized velocity product over a large glacier region of roughly 600 km by 200 km. Velocities are at a monthly resolution and at 300 m resolution, making all kinds of glacier dynamics observable.

By combining reanalysis, weather station and satellite data, we show that increases in surface melt over Greenland are initiated by large-scale precipitation events year-round. Estimates from a regional climate model suggest that the initiated melting more than doubled between 1988 and 2012, amounting to ~28 % of the overall melt and revealing that, despite the involved mass gain, precipitation events are contributing to the ice sheet's decline.

Cold-ice processes may be widespread within temperate glacier systems but the role of cold-ice processes in temperate glacier systems is relatively unknown. Climate forcing is the main control on glacier mass balance but potential for heterogeneous thermal conditions at temperate glaciers calls for improved model assessments of future evolution of thermal conditions and impacts on glacier dynamics and mass balance. Cold-ice processes need to be included in temperate glacier land system models.

The perennial snow, or firn, on the Greenland ice sheet each summer stores part of the meltwater formed at the surface, buffering the ice sheet’s contribution to sea level. We gathered observations of firn air content, indicative of the space available in the firn to retain meltwater, and find that this air content remained stable in cold regions of the firn over the last 65 years but recently decreased significantly in western Greenland.

A method to measure the snow freeboard of Antarctic sea ice from CryoSat-2 data is developed. Through comparisons with data from airborne campaigns and another satellite mission, we find that this method can reasonably retrieve snow freeboard across the Antarctic and shows promise in retrieving snow depth in certain locations. Snow freeboard data from CryoSat-2 are important because they enable the calculation of sea ice thickness and help to better understand snow depth on Antarctic sea ice.

We present ice sheet modeling results of ice retreat over southwestern Greenland during the last 12 000 years, and we also test the impact that model horizontal resolution has on differences in the simulated spatial retreat and its associated rate. Results indicate that model resolution plays a minor role in simulated retreat in areas where bed topography is not complex but plays an important role in areas where bed topography is complex (such as fjords).

Estimating glacier changes involves measuring elevation changes, often using elevation models derived from satellites. Many elevation models have data gaps (voids), which affect estimates of glacier change. We compare 11 methods for interpolating voids, finding that some methods bias estimates of glacier change by up to 20 %, though most methods have a smaller effect. Some methods produce reliable results even with large void areas, suggesting that noisy elevation data are still useful.

This study shows how complex and varied the processes are that determine the frontal position of tidewater glaciers. Rather than uniform melt or calving rates, a single (medium-sized) glacier can feature regions that retreat almost exclusively due to melting and other regions that retreat only due to calving. This has far-reaching consequences for our understanding of how glaciers retreat or advance.

Rock glacier flow varies on multiple timescales. The variations have been linked to climatic forcing, but a quantitative understanding is still missing. We use a 1-D numerical modelling approach coupling heat conduction to a creep model in order to study the influence of temperature variations on rock glacier flow. Our results show that heat conduction alone cannot explain the observed variations. Other processes, likely linked to water, must dominate the short-term velocity signal.

Evaluation of the vertical precipitation rate profiles of CloudSat radar by comparison with two surface-based micro-rain radars (MRR) located at two antarctic stations gives a near-perfect correlation between both datasets, even though climatic and geographic conditions are different for the stations. A better understanding and reassessment of CloudSat uncertainties ranging from −13 % up to +22 % confirms the robustness of the CloudSat retrievals of snowfall over Antarctica.

Unmanned Aerial Vehicles (UAVs) are increasingly common tools in the geosciences, but their use requires good ground control in order to make accurate georeferenced models. This is difficult in applications such as glaciology, where access to study sites can be hazardous. We show that a new technique utilising on-board GPS post-processing can match and even improve on ground-control-based methods, and, as a result, can produce accurate glacier velocity fields even on an inland ice sheet.

Observed summer Arctic sea ice retreat has been faster than simulated by the average CMIP5 models, most of which exclude falling ice particles from their radiative calculations. We use controlled CESM1-CAM5 simulations to show for the first time that snowflakes' radiative effects can accelerate sea ice retreat. September retreat rates are doubled above current CO₂ levels, highlighting falling ice radiative effects as a high priority for inclusion in future modelling of the Arctic.

Modifications in ice-stream networks have major impacts on ice sheet mass balance and global sea level. However, the mechanisms controlling ice-stream switching remain poorly understood. We report a flow switch in an ice-stream system that occurred on the Baffin Island shelf through the erosion of a marginal trough. Up-ice propagation of ice streams through marginal troughs can lead to the piracy of neighboring ice catchments, which induces an adjacent ice-stream switch and shutdown.

In March 2007, the Leñas Glacier in the Central Andes of Argentina collapsed and released an ice avalanche that travelled a distance of 2 km. We analysed aerial photos, satellite images and field evidence to investigate the evolution of the glacier from the 1950s through the present day. A clear potential trigger of the collapse could not be identified from available meteorological and seismic data, nor could a significant change in glacier geometry leading to glacier instability be detected.

The paper facilitates the construction of a satellite-derived 2 m air temperature (T_2m) product for Arctic snow/ice areas. The relationship between skin temperature (T_skin) and T_2m is analysed using weather stations. The main factors influencing the relationship are seasonal variations, wind speed and clouds. A clear-sky bias is estimated to assess the effect of cloud-limited satellite observations. The results are valuable when validating satellite T_skin or estimating T_2m from satellite T_skin.

Baffin Bay serves as a huge reservoir of sea ice which provides solid freshwater sources for the seas downstream. Based on satellite observations, significant increasing trends are found for the annual sea ice area flux through the three gates. These trends are chiefly related to the increasing ice motion which is associated with thinner ice owing to the warmer climate (i.e., higher surface air temperature and shortened freezing period) and increased air and water drag coefficients.

How ocean-induced melt under floating ice shelves will change as ocean currents evolve remains a big uncertainty in projections of sea level rise. In this study, we combine two of the most recently developed melt models to form PICOP, which overcomes the limitations of past models and produces accurate ice shelf melt rates. We find that our model is easy to set up and computationally efficient, providing researchers an important tool to improve the accuracy of their future glacial projections.

Measurements of surface roughness are rare on glaciers, despite being an important control for heat exchange with the atmosphere and surface melt. In this study, roughness values were determined through measurements at multiple locations and seasons and found to vary across glacier surfaces and to differ from commonly assumed values in melt models. Two new methods that remotely determine roughness from digital elevation models returned good performance and may facilitate improved melt modelling.